The invention relates to a loop-forming element, particularly for knitting and warp knitting machines.
For loop-forming machines, such as knitting or warp knitting machines, knitting tools are known that comprise a needle (also known as a loop-drawing needle) and a transfer needle. The loop-drawing needle and the transfer needle are provided with hooks pointing toward one another and are disposed in a common needle track. By a relative motion of the loop-drawing needle and the transfer needle, loops can be transferred between the two needles. The loop-drawing needle can also pull a loop that it has received through a loop received by the transfer needle (drawing a new loop through the old loop). An important factor here is that the hook tip of the loop-drawing needle find its way through the loop held by the transfer needle, without piercing the yarn itself.
One such knitting tool is known from International Patent Disclosure WO 02/072936 A2. The loop-drawing needle has a shank which is provided with a hook on the end. In the region of the hook, the shank is relatively slender, so that the hook width is less than the width of the rest of the shank of the loop-drawing needle. In the region of its cheek, the shaft of the loop-drawing needle is provided with a recess, which serves to receive the transfer hook of the transfer needle. The transfer hook, toward the tip of its hook, is provided with a step on both sides, forming a narrow, noselike protrusion that fits into the recess (noucat) embodied in the cheek of the loop-drawing needle.
In at least one embodiment of the knitting tool known from WO 02/027936, a control face is embodied adjoining the cheek of the loop-drawing needle, and a protrusion embodied on the transfer needle runs along this control face. When the protrusion moves past the ramplike control face, the spacing between the loop-drawing needle and the transfer needle changes. On the one hand, this creates the basis for the ability of the hook of the loop-drawing needle and the hook of the transfer needle to move past one another unhindered, and for the hook of the transfer needle on the other hand to plunge into the noucat embodied in the cheek of the needle. In this version, the needle hook is set back from the cheek by the amount of the penetration depth of the transfer hook; that is, the cheek height is higher, by the depth to which the transfer hook penetrates, than the upper edge of the hook of the loop-drawing needle. In another version known from the above patent disclose, the top edge of the needle hook is aligned with the cheek height, and the transfer hook in its return stroke executes a slight transverse motion to dip into the cheek of the needle. With this version, smaller loop heights can be achieved. To achieve the slight transverse motion, however, a spring prestressing means is provided, which permanently presses the transfer needle against the loop-drawing needle. Every relative motion in this case generates friction, which can cause unwanted heating.
With the prior art above as the point of departure, it is the object of the invention to create a knitting tool, of the type defined at the outset, which is not overly sensitive in terns of the loop forming process and especially with regard to the variety of yarns that can be used, and which is reliable and robust.